Under the North Korean Freedom Act, any North Korean arriving on US soil can claim asylum. I know of one instance where this was denied, by an American bitchocrat who by denying NKers their asylum let them fall into Chinese hands, which meant they would eventually fall back into the hands of Kim Jeongil, which means...

They are dead.

Escaping from North Korea is a treasonous offence for which the penalty is usually execution. If you're lucky, you just get sent to a concentration camp.